https://tejhq.dev/blog Engineering deep-dives and unhedged opinions on Indian-market data infrastructure. en-IN Sun, 07 Jun 2026 12:43:21 GMT https://tejhq.dev/blog/sixteen-years-nse-bhavcopy https://tejhq.dev/blog/sixteen-years-nse-bhavcopy Sat, 06 Jun 2026 00:00:00 GMT What it took to backfill NSE end-of-day prices from 2010 to today: two URL schemes, two CSV schemas, a SEBI format cutover in the middle, and a Go SQL driver that hates NULL. bhavcopynsebackfillengineering https://tejhq.dev/blog/corp-actions-adjustment-engine https://tejhq.dev/blog/corp-actions-adjustment-engine Tue, 12 May 2026 00:00:00 GMT Splits, bonuses, dividends, ISIN drift across mergers. How TejHQ Phase 4 actually shipped: the adjustment math, the per-ISIN reverse cumprod, the post-merger ISIN resolver, and the 89% Yahoo reconciliation. corp-actionsengineeringphase-4adjusted-closereconciliation https://tejhq.dev/blog/nifty-500-momentum-backtest-polars https://tejhq.dev/blog/nifty-500-momentum-backtest-polars Fri, 03 Apr 2026 00:00:00 GMT Twelve-minus-one momentum, monthly rebalance, top decile, 2024-Q1 to 2026-Q1. From raw Bhavcopy to equity curve in one script. Full code + results. backtestingpolarsmomentumnifty https://tejhq.dev/blog/indian-market-data-pricing-explained https://tejhq.dev/blog/indian-market-data-pricing-explained Thu, 12 Mar 2026 00:00:00 GMT Why retail quants in India pay anywhere from zero to twenty-four lakh rupees a year for the same OHLCV. A breakdown of who charges what, and what they're actually selling. industrypricingnsebse https://tejhq.dev/blog/polars-vs-duckdb-india-eod-benchmark https://tejhq.dev/blog/polars-vs-duckdb-india-eod-benchmark Sun, 08 Feb 2026 00:00:00 GMT Same data, same query, two engines. Polars wins on pure scan speed; DuckDB wins on remote Parquet pruning. Numbers, code, and the cases where each loses. polarsduckdbbenchmarkparquet https://tejhq.dev/blog/bhavcopy-pipeline-from-zero https://tejhq.dev/blog/bhavcopy-pipeline-from-zero Thu, 15 Jan 2026 00:00:00 GMT End-of-day market data for India costs anywhere from ₹0 to ₹24 lakh a year. We pay zero. Here's the SEBI CMTS Bhavcopy pipeline that powers tej-bazaar. pipelinebhavcopynsebse